Cropico RH9A Manual 610028 Rev6

RH9A SeriesHigh Resistance Decade Boxes

Operating Instructions

Bracken Hill, South West Industrial Estate,Peterlee, Co. Durham SR8 2SW. England.Tel: +44 (0)191 586 3511 Fax: +44 (0)191 586 [email protected]

Operating InstructionsRH9A Series High Resistance Decade Boxes

Limited Warranty & Limitation of LiabilityCROPICO guarantees this product for a period of 1 year.The period of warranty will be effective at the dayof delivery.

(c) Copyright 2008All rights reserved. Nothing from this edition may bemultiplied, or made public in any form or manner, eitherelectronically, mechanically, by photocopying, recording,or in any manner, without prior written consent fromCROPICO. This also applies to accompanying drawingsand diagrams.

Due to a policy of continuous development CROPICOreserves the right to alter the equipment specificationand description outlined in this publication withoutprior notice and no part of this publication shall bedeemed to be part of any contract for the equipmentunless specifically referred to as an inclusion withinsuch contract.


Disposal of Old Product

This product has been designed and manufactured withhigh quality materials and components that can berecycled and reused.

When the crossed out wheelie bin symbol is attached toa product it means the product is covered by theEuropean Directive 2002/96/EC.

Please familiarise yourself with the appropriate localseparate collection system for electrical and electronicproducts.

Please dispose of this product according to localregulations. Do not dispose of this product along withnormal waste material. The correct disposal of thisproduct will help prevent potential negativeconsequences for the environment and human health.

User Note:These Operating Instructions are intended for the use ofCompetent Personnel.


CONTENTS

Introduction 3

Unpacking Instructions 4

Specification 5

Routine Maintenance 7


3

Introduction

The Cropico RH9A series is a range of high resistanceprecision decade boxes. Featuring 1, 3, 6, and 9 dials, theyoffer resistances up to 1 Terraohm. Each instrument is builtusing specially aged precision thick film or metal filmresistors that are mounted directly onto the purposedesigned decade switches.

The RH9A is useful as a laboratory tool or referencestandard wherever low current and high resistances areencountered. A typical application would be in thecalibration of insulation testers.


4

Unpacking Instructions

Your RH9A has been thoroughly tested and inspectedbefore shipping. Unless a special calibration has beenrequested a Cropico "In-house" calibration certificate willalso be included. Therefore the instrument is ready for useafter unpacking. However, it is recommended that theinstrument is checked for any damage that may haveoccurred in transit. In the unlikely event that damage hasoccurred, all packing materials should be retained andCropico Ltd. or the local agent should be contacted forfurther instructions.

The RH9A comes complete and ready for use. The packageshould contain:-

a) The instrumentb) 2 Input Connectors with connection cable c) Test Certificated) Certificate of Conformitye) Instructions for use


5

Specification

To ensure permanence of calibration the figures for themaximum Voltage on each decade should not beexceeded.

Connection is made to the RH9A by means of specialhigh voltage plugs and sockets which should always beused. Each plug is fitted with a high voltage cable.

When using the instrument set the required dial settingon the RH9A before applying the voltage from the devicebeing tested.

Before altering the resistance setting of the RH9A alwaysswitch off the applied voltage from the device beingtested to avoid the possibility of actually switching 5kVd.c. which could be harmful to the RH9A.

When using the higher values on the RH9A i.e. above asetting of 1GW the following comments should be noted.

1. Connection leads should be kept as short as possible

2. Having set the dials on the RH9A and the test objectswitched on, the operator should stand away from theinstrument and avoid moving as this could influence themeasurement and give an unstable reading.

Switch Settings

1 k

10 kohm

100 kohm

1 Megohm

10 Megohm

100 Megohm

1 Gigohm

10 Gigohm

100 Gigohm

1 Tera-ohm

Accuracy

±0.1%

±0.1%

±0.1%

±0.1%

±1%

±1%

±1%

±1%

±2%

±2%

Max Volts dc

25 V

100 V

250 V

500 V

4,000 V

4,000 V

4,000 V

5,000 V

5,000 V

5,000 V

Power Rating

1 Watt

1 Watt

1 Watt

1 Watt

1.5 Watts

1.5 Watts

3.5 Watts

3.5 Watts

1.3 Watts

1.3 Watts

Temp. Coeff.

±50 ppm/˚C

±50 ppm/˚C

±50 ppm/˚C

±50 ppm/˚C

±100 ppm/˚C

±100 ppm/˚C

±100 ppm/˚C

±100 ppm/˚C

±2,000 ppm/˚C

±2,000 ppm/˚C


6

3. It should be noted that an operator moving near thetest and wearing synthetic clothing will cause unstablereadings.

4. Using high resistance settings on the RH9A and havinga low test voltage on the device being tested requires alot of patience as the test currents involved are very lowand it may take some time to resolve a final reading.

5. Measurement of high resistance values is dependentupon

a) Relative humidityb) Ambient temperaturec) Measuring timed) Polarity of test voltagee) Previous test voltages applied

6. If the value to be selected is equivalent to the firstposition of the dial, always use position 10 on theprevious dial, this will have a better uncertainty ofmeasurement. This is of course, subject to the max voltsfor the dial used not being exceeded.

7. The earth terminal mounted on the top panel should beconnected to earth to ensure operation safety andminimise measurement errors.

Terminals

Dimensions and Weight

Dimensions

Weight

RH9A-#

47cm x 37cm x 19cm

8.8 Kg.

RH9A-5

22cm x 11cm x 9cm

0.8 Kg.

2 x

1 x 4mm

Special Shrouded Plug Sockets

Binding Post

Hi and Lo Connections

Ground Connection


7

Routine Maintenance

With normal usage the RH9A requires little or nomaintenance. The special insulators around the High andLow input sockets should be kept clean to avoid theshunting effect of accumulated dirt and grease. Wipingwith an alcohol moistened cloth should be sufficient tomaintain accuracy.

If the instrument is removed from its case for any reason,the resistors must never be touched with the fingers.Touching the resistors will seriously effect the calibrationof the instrument and may cause progressivedeterioration of accuracy.

Calibration of the RH9A requires a PrecisionTerraohmmeter and a Resistance Bridge such as aWheatstone or a Comparator Bridge with another RH9Awith known calibration for comparison.

Replacement of individual resistors is not recommendedas resistors are selected and matched by Cropico as partof each decade to maintain the specified accuracythroughout the entire resistance range.

Should switch lubrication ever be required, only a puresilicone lubricant should be applied very sparingly.Ordinary switch lubricants may have a low leakageresistance, which will change the calibration of the higherresistance decades.


8

For Technical Support Contact:

Tel: +44 (0) 191 587 8718

For Service and Calibration Contact:

Service DepartmentSeaward GroupUnit 11Bracken HillSouth West Industrial EstatePeterleeCo DurhamSR8 2LSEngland

Tel: +44 (0) 191 587 8739Fax: +44 (0) 191 587 8737E-mail: [email protected]

G R O U P

CROPICO is a division of

SEAWARD


9

Additional Products From Cropico

DIGITAL OHMMETERS

RESISTANCE BRIDGES

RESISTANCE DECADE BOXES

RESISTANCE STANDARDS

DIGITAL THERMOMETERS

THERMOCOUPLE SIMULATORS

PT100 SIMULATORS

INSULATION TEST SETS

UNIVERSAL CALIBRATORS

HIPOT TESTERS

ELECTRICAL SAFETY TESTERS

Phone, fax or e-mail for further information on the aboveor for a copy of our general catalogue:

Phone: +44 (0) 191 586 3511Fax: +44 (0) 191 586 0227E-mail: [email protected]: www.cropico.com

610028 Rev 6

Cropico RH9A Manual 610028 Rev6

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